BACKGROUND: Among the spectrum of the tick-borne infections, Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are most often recorded in the Tomsk region, however it is obviously that possible range of the pathogens is not limited to these ones. AIM: is to assess epidemic process manifestations and detect frequencies of pathogen’s markers of tick-borne infections among adult patients applying serological and molecular genetic techniques in the Tomsk region during 2020–2023. METHODS: A single-center prospective sample study was conducted applying a comprehensive approach in peripheral blood specimens obtained from 197 patients with suspected tick-borne infections hospitalized during 2020–2023. To verify the diagnoses of TBE or LB, specific immunoglobulins of classes M and G to the antigens of TBE virus and Borrelia burgdorferi s. l. were determined in paired blood serum samples applying enzyme-linked immunosorbent assay (ELISA). Additionally, the polymerase chain reaction (PCR) was used to detect genetic markers of TBE virus, B. burgdorferi s.l., B. miyamotoi, Rickettsia spp., Coxiella burnetii, and Francisella tularensis. Epidemiological surveillance data of incidence rates of tick-borne infections obtained from official reports were analyzed as well. MS Office Excel 2010 software was used to calculate frequency morbidity measures. RESULTS: We verified the final diagnosis of TBE in 52 (26.4%) patients, LB in 116 (58.9%) patients, co-infection of TBE and LB 15 (7.6%) patients, hard tick relapsing fever caused by B. miyamotoi in 8 (4.1%) patients, coinfection of Q fever caused by C. burnetii with TBE or LB in 4 (2.0%) patients, and coinfection of tularemia with TBE or LB in 2 (1.0%) cases. We identified markers of TBE and LB pathogens by PCR in 3.6% and 4.1% of the patients. Most number of individuals with tick bites, and the highest LB and TBE incidence rates were recorded in the suburbs of Tomsk. The age groups of 40‒59 years, and elderly people 60 years and older were predominated among the patients. CONCLUSION: It was found out that, in addition to LB and TBE, there were such tick-borne infections as tick relapsing fever, Q fever, and tularemia in the Tomsk region in the 2020–2023 period.

Aim. To perform a comparative assessment of subset composition and functional activity of peripheral blood lymphocytes in patients with tick-borne encephalitis (TBE) and ixodid tick-borne borreliosis (ITBB) in the acute phase of the disease.Materials and methods. The study involved 22 patients with febrile and meningeal TBE, 15 patients with ITBB with and without erythema, and 11 healthy controls. Subset composition of blood lymphocytes was determined by flow cytometry. The blast transformation assay was applied to assess lymphocyte proliferation. Cytokine-producing activity of cells was studied in 24-hour incubated mononuclear cell cultures. Cytokine concentrations (interleukin (IL)-2, IL-4, IL-10, interferon (IFN)γ) were determined in the supernatants by the enzyme-linked immunosorbent assay (ELISA).Results. Patients with TBE demonstrated an increase in the proportion of helper – inducer T-cells, a pronounced decrease in the proportion and absolute count of cytotoxic T cells, and low T lymphocyte count compared to the control values. The study in ITBB patients revealed an increase in the helper – inducer T-cell count and the proportion of NK-cells, a decrease in the cytotoxic T cell count, and the T lymphocyte count comparable to normal values. The most significant decrease in the levels of phytohemagglutinin-induced lymphocyte proliferation was found in patients with TBE. Patients of both groups showed a decrease in IL-2 secretion in the mononuclear cell culture, a rise in IL-4 and IL-10 production, and IFNγ production levels comparable to control values.Conclusion. The study of TBE patients revealed relative lymphocytopenia with changes in the subset composition of lymphocytes characterized by an increase in the proportion of helper – inducer T-cells and a decrease in the absolute cytotoxic T lymphocyte count. Patients with ITBB demonstrated an increase in the proportion of NK-cells and a more pronounced imbalance in the T-helper / cytotoxic T lymphocyte ratio. Changes in the functional phenotype of lymphocytes, regardless of the etiology of tick-borne infection, were characterized by reduced proliferative reserve, low IL-2 secretion, increased IL-4 and IL-10 production, and depressed reactivity of lymphocytes with respect to IFNγ secretion.

The aim of the study was to evaluate the antimicrobial effect of single and repeated nitric oxide (NO) exposure on the major pathogens of nosocomial pneumonia isolated from the sputum of cardiac surgery patients.Materials and Methods. A 24-hour culture of microorganisms from pan-resistant isolates of Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and Klebsiella pneumoniae from the sputum of inpatient cardiac surgery patients with nosocomial pneumonia, as well as strains of P. aeruginosa and E. coli from the American Type Culture Collection (ATCC), were exposed to 200 ppm NO (experimental sample) or medical air (control sample) in a sealed chamber for 30 minutes. After a single or 4 repeated gas exposure at 4 h intervals, Petri dishes were placed in a thermostat at 37°C and the results were evaluated at 24 and 48 h or at 12, 24, 36 and 48 h, respectively. Grown colonies were counted using an automated colony counter and recorded as CFU/mL.Results. No growth of clinical isolates of P. aeruginosa and E. coli was observed 24 and 48 h after a single exposure to NO. Growth of A. baumannii was lower compared to controls at 24 h but continued at 48 h. No effect of a single exposure to 200 ppm NO on other microorganisms was observed. After 4 exposures to NO, the growth of ATCC E. coli was not detected, the growth of other experimental strains was significantly lower compared to the control (P<0.05).Conclusion. Our results provide a rationale for the use of multiple intermittent inhalation of 220 ppm NO for the treatment of patients with hospital-acquired bacterial pneumonia.

The uncontrolled use of antibiotics has led to a global problem of antimicrobial resistance. One of the main mechanisms of bacterial resistance is the formation of biofilms. In order to prevent the growth of antimicrobial resistance, it is crucial to develop new antibacterial agents that are capable of inhibiting the formation of biofilms. This makes this area of research highly relevant today. Promising candidates for these antibacterial agents are new bionanomaterials made from natural humic substances and silver nanoparticles. These substances have the potential to not only directly kill microorganisms but also penetrate biofilms and inhibit their formation. The goal of this study is to synthesize active pharmaceutical substances in the form of bionanomaterials, using ultradispersed silver nanoparticles in a matrix of coal humic substances, perform their characterization (NMR spectroscopy, TEM, and ICP-AES methods), and research their influence on biofilm formation in the most dangerous opportunistic pathogens (E. coli, Methicillin-resistant St. Aureus, K. pneumoniae, P. aeruginosa, St. aureus, A. baumannii, and K. Pneumonia). The results showed that all of the studied bionanomaterials had antibacterial activity against all of the opportunistic pathogens. Furthermore, they were found to have a suppressive effect on both pre-existing biofilms of these bacteria and their formation.

Introduction. Studies aimed at identifying pathogenetic features of tick-borne natural focal infections depending on etiological agent are relevant to seek out for new associations of biomarkers characterizing the structural and functional phenotype of immune cells significant for the differential diagnosis and prognosis of diseases. The aim of the study was to evaluate the parameters of a leukogram with an expanded profile in relation to the parameters of cytokine status in patients with viral tick-borne encephalitis as well as erythemic tick-borne borreliosis at acute stage of the disease. Materials and methods. The study involved 28 patients with the non-erythemic tick-borne borreliosis and 27 patients with tick-borne encephalitis at the acute stage of the disease, as well as 16 healthy individuals (control group). Venous blood samples were examined using a Sysmex XN1000 analyzer based on reflex testing technology with extended profile allowing to characterize leukocyte reaction during infection and inflammation, including parameters such as the absolute and relative count of immature granulocytes (IG), neutrophil granularity index (NEUT-GI), neutrophil reactivity index (NEUT-RI), count of reactive lymphocytes (RE-LYMP), count of antibody-producing lymphocytes (AS-LYMP). Concentrationof IL-2, IL-4, IL-6, IL-8, IL-10, IFN and TNF in blood serum was determined by enzyme immunoassay using specific reagent kits (Vector-Best, Russia). Results. It was found that changes in the quantitative composition of blood leukocytes in patients with viral tick-borne encephalitis and non-erythemic form of tick-borne borreliosis have a unidirectional tendency characterized by increased count of metabolically active neutrophils (NEUT-RI) and a decreased count of reactive lymphocytes (RE-LYMP) compared to healthy individuals. Changes in the leukogram occur along with high blood concentration of proinflammatory cytokines IL-8 and TNF and a low level of IFN. A positive direct correlation was revealed between the fluorescence intensity parameter characterizing the metabolic activity of neutrophil granulocytes (NEUT-RI) and blood serum IL-8 level both in tick-borne encephalitis (r = 0.422, p 0.05) and non-erythemic form of tick-borne borreliosis (r = 0.551, p 0.05). Additionally, in the former, a positive correlation was established between the total leukocyte count (WBC) and concentration of TNF in the blood serum (r = 0.532, p 0.05).

The aim of the review was to analyze modern experimental studies and clinical trials aimed at assessing metabolic activity of gut microbiota in bronchial asthma (BA) and helminth infections. Being one of the most common chronic heterogeneous respiratory diseases, bronchial asthma secures its place among global health problems of great socioeconomic importance. In recent years, a lot of data has been accumulated indicating that the state of gut microbiota is an important factor determining the state of human health and affecting immune mechanisms underlying the development of allergic diseases in childhood. Dysbiosis of gut microbiota is due not only to changes in its composition, but also to disturbances in its metabolism. In accordance with the “gut – lung axis” concept, maintaining healthy gut microbiota and correcting its disorders, including strategies aimed at activating synthesis of short-chain fatty acids in the intestine, may become a new way to prevent and treat chronic respiratory diseases in childhood. In turn, experimental and epidemiological studies have shown the immunomodulatory activity of helminths. It is assumed that their impact on the composition and function of gut microbiota is one of the mechanisms by which helminths influence the immune response of the host and the course of BA.

Relevance. According to official data, in 2020 in Russia, Ixodic tick-borne borreliosis took the leading position in the prevalence and registration frequency among tick-borne infections, which amounted to 38.5% of all cases of natural focal transmissible infections. In the Tomsk region for many years, the average long-term incidence of Ixodic tick-borne borreliosis exceeds the Russian one by more than 3 times. Aim. Identify features the features of the clinical and epidemiological manifestations of the Ixodic tick borne borreliosis foci in the Tomsk region; to identify priority areas for carrying out problem-oriented research in the field of ecology, epidemiology and the clinic of borreliosis infection in the Tomsk region. Materials and methods. The material for the study was the data of the federal statistical observation form «Information on infectious and parasitic morbidity» for the 2015-2020. The materials of 713 cases of Ixodic tick-borne borreliosis disease and more than 125 thousand appeals to medical organizations of the region regarding the tick bites, registered in official registration forms, were studied. As part of the annual epidemiological monitoring for a six-year period, 1200 specimens of Ixodid ticks collected in natural biotopes of the Tomsk region were examined for the presence of Borrelia DNA, depending on their genus (Ixodes and Dermacentor). DNA detection of Borrelia burgdorferi sensu lato complex (B. burgdorferi, B. garinii, B. afzelii) and B. miyamotoi was performed by real-time PCR. Results. The high number of ixodid ticks in local areas of natural biotopes (up to 200.0 specimens/km at the height of the epidemiological season), as well as the failure to comply with personal prevention measures, determines a consistently high rate of referral of the population of the Tomsk region to medical organizations due to tick bites. The number of requests annually averages 20.8 thousand. As a result of an annual study using PCR tests of ticks taken from people who applied to emergency prevention centers, Borrelia DNA was detected on average in 40% of samples; blood samples from individuals affected by tick bites were positive on average in 3.7% of cases. In the period 2015-2019 spirochetes B. garinii and B. afzelii were most often found in the tissues of ixodid ticks. Since 2020, the species Borrelia miyamotoi has been included in the list of pathogenic borrelia species to be monitored in the Tomsk region – spontaneous infection of ticks (Ixodes) was 3%. The maximum values both in the number of patients with ixodic tick-borne borreliosis and in the density of infections per 10,000 hectares (90-110 cases) are observed in the south of the Tomsk region (Asinovskyi, Kozhevnikovskyi, Krivosheinskyi, Tomskyi, Shegarskyi districts, the city of Tomsk). In the epidemic season of 2020, the number of laboratory-confirmed cases of non-erythema ixodic tick-borne borreliosis was more than 2.5 times higher than the number of diseases with skin manifestations. Conclusion. The large number of ixode mites in natural biotopes, the high degree of their infection with pathogenic spirochetes indicate the presence of active natural foci of ixodic tick-borne borreliosis in the Tomsk region. The study of the genotypic diversity of pathogenic borrelias in relation to the species diversity of vectors, the analysis of the clinical manifestations of different etiological variants of tick-borne borreliosis (mono- and mixed infections), as well as the development of an algorithm for differential diagnostic search and a model for predicting the outcomes of the infectious process in tick-borne borreliosis and mixed infections are priority directions of problem-oriented scientific research in Tomsk region.

BACKGROUND: Knowledge about the infectious potential of the causative agent of recurrent tick-borne fever Borrelia miyamotoi and the role of this pathogen in the etiological structure formation of transmissible natural focal infections in a number of regions remains incomplete. Among them is the Tomsk region where in 2021 the incidence of ixodic tick-borne borreliosis was 15.7 per 100,000 population, which is 3.6 times higher than the all-Russian indicator. AIMS: This study aimed to summarize and analyze epidemiological data, as well as the results of our own clinical observations and laboratory studies conducted in 20152021 confirming the distribution of the causative agent of relapsing tick-borne fever B. miyamotoi in the Tomsk region. MATERIALS AND METHODS: Epidemiological data on the manifestation of the natural foci of tick-borne infections were analyzed in the Tomsk region for the period 20152021. A clinical case of febrile infection caused by B. miyamotoi infection is described as an example of underdiagnosis of relapsing tick-borne fever. Verification of the etiological variant of borreliosis was carried out using real-time PCR. DNA extraction and detection of B. miyamotoi genetic markers were performed using RealBest series kits (Vector-Best, Novosibirsk), followed by nucleic acid sequencing of B. miyamotoi 23SrRNA, glpQ, and recA gene sequences. Ixodid ticks (Ixodes persulcatus, Ixodes pavlovskyi, Dermacentor reticulatus) collected from the Tomsk region were studied for infestation with B. miyamotoi. The detection of genetic markers of pathogenic Borrelia was carried out in nucleic acid samples isolated from tick homogenates using kits of the RealBest series (Vector-Best, Novosibirsk). RESULTS: In 2016, the first clinical case of borreliosis caused by B. miyamotoi was confirmed by molecular genetic methods in the Tomsk region. During the period 20152021, the infection rate of B. miyamotoi ticks of the genus Ixodes in the Tomsk region was up to 7%, ticks of the genus Dermacentor ― up to 3%. CONCLUSION: The results of this study demonstrated the distribution of the causative agent of relapsing tick-borne fever B. miyamotoi in the natural foci of the Tomsk region, which requires further monitoring of the epizootic situation and study of the role of this pathogen in the formation of the etiological structure of transmission natural focal infections.

Federal state educational standards aim at formation of the students’ competences, whichare treated as an objective of learning. Development of students’ competencies takes place, in particular, in project-based training, which has been approved in a course of microbiology and in an interdisciplinary educational program for specialty “Medical cybernetics”. An interdisciplinary approach reveals the additional advantages of project-based education.

The article presents the results of the preclinical study of the immunocorrective properties of the total ethanol extract from the raw material of the medicinal plant of the traditional medicine of Siberia – Coluria geoides (Pall.) Ledeb.), Rosaceae. The eff ect of extract on the phagocytic activity of peripheral blood neutrophils and the main indicators of the humoral immune response (the number of antibody-forming cells of the spleen and the synthesis of anti-erythrocyte antibodies) were evaluated on a model of experimental immunodefi ciency in inbred mice. Extract from raw materials C. geoides showed a pronounced immunomodulatory eff ect, in some parameters superior to the eff ect of offi cinal tincture of Echinacea.

Background. Nowadays many efforts are taken in searching for Parkinson’s disease biomarkers, especially for an early recognition of the disease. The gut microbiota is one of the potential sources of biomarkers, changes in the composition of which in PD are actively studied. The aim of this study is to identify microbiota biomarkers in the Parkinson’s disease with an estimated accuracy of the diagnostics, including differential diagnostics, relative to other neurological diseases for patients of the Russian population. Material and methods. One hundred ninety-two metagenomics profiles from patients with Parkinson’s disease (n = 93), people with other neurological diagnoses (n = 33), and healthy controls (n = 66) were included in this study. These profiles were obtained with amplicon sequencing of bacterial 16S rRNA genes. Classifying models were made using the naive Bayes classifier, the artificial neural network, support vector machine, generalized linear model, and partial least squares regression. As a result we established that an optimal classification by the composition of the gut microbiota on the validation sample (sensitivity 91.30%, specificity 91.67% at 91.49% accuracy) amid patients was demonstrated with a naive Bayes classifier using the representation of the following genera as predictors: Christensenella, Methanobrevibacter, Leuconostoc, Enterococcus, Catabacter, Desulfovibrio, Sphingomonas, Yokenella, Atopobium, Fusicatenibacter, Cloacibacillus, Bulleidia, Acetanaerobacterium, and Staphylococcus. Conclusions. Information of the gut microbiota taxonomic composition may be used in differential diagnosis of Parkinson’s disease.

Purpose of the study: working out an easy-to-use complication development index (CDI), designing a program for post morbidity rehabilitation of patients with surgical infection to improve the results of its treatment and reduce lethality. Materials and methods. A retrospective results analysis of treatment of 320 patients for purulent peritonitis and abdominal sepsis was carried out, including 268 patients (the comparison group) and 52 (the core group) with whom the complications development index was calculated. While studying this group of patients, the same protocol was used to prevent and treat complications on the basis of a complex individual program. In the comparison group, the patients were divided according to the severity of their condition in compliance with generally accepted clinical criteria: medium-heavy (98), severe (86) and extremely severe (84 patients, respectively). We have studied general clinical and biochemical indices, as well as the results of instrumental studies of the function of vital organs and body systems. The following indices were calculated: the prothrombin index; the integral index of thromboelastography (IIT), J = [R (min) × K (min)] : mA (mm), where R is the clotting time, K is the clot formation time, mA is the clot density); the general condition severity APACHE II (Acute physiology and chronic health evaluation); the degree of organ dysfunction SOFA (Sepsis organ failure assessment); leukocyte index of intoxication (LII). The PIRO concept (predisposition, infection, response, organ dysfunction) was used for clinical interpretation of the received research results. Results. The prediction index of complications of surgical infection was proposed. It is based on the results of clinical analysis the results of patient treatment and calculated by using the severity of the underlying pathological process, as well as the number of concomitant diseases, pathological syndromes and aggravating factors. As a result of the complication development prediction index use along with the implementation of the complex program for prevention and treatment of complications, the number went down from 50% to 90% in different groups under observation.

This review generalizes the current evidence on the content of the pro- and anti-inflammatory cytokines in patients’ blood serum with atherosclerotic lesions of the coronary, carotid and iliac arteries. The results gave the ability to assess cytokine immune cells of atherosclerotic plaques. Also the results of national and international research allowed the assessment of the prognostic value of cytokine content.

The numerical density of secretory granules dense-core vesicles (DCV) in the cytoplasm of pinealocytes of the pineal gland was estimated by transmission electron microscopy in male white mice and Wistar rats. The 3-day biorhythm and lunaphase changes in the DCV content in the perikaryon and the processes of pinealocytes, which are manifested significantly in different seasons of the year, are established. The three-day biorhythm in adult male mice in comparison with younger male rats is not expressed uniformly in different phases of the moon. The in-phase manifestation of infradian biorhythms in different species of animals during the year with an unchanged daily photophase indicates the existence of common external synchronizers for mammals of these biorhythms that are not associated with the light/dark cycle.

Purpose: this study morphological changes the exorbital lacrimal glands at experimental impact on an organ of vision of high-intensity light.Material and methods. White not purebred rats males (n = 40) were subjected to continuous influence of light intensity by 3500 lx within 1, 7, 14 and 30 days, the control group (n = 10) contained in conditions of natural lighting (20 lx). Exorbital lacrimal glands fixed in formalin, embedded in paraffin wax, stained hematoxylin-eosine. By means of an oculary insert of Avtandilov counted specific volumes of output channels, an epithelium, stroma and vessels of exorbital lacrimal glands, defined an epitelio/stroma ratio. The analysis of data was carried out by methods of descriptive statistics with calculation of a median (Ме) and interquartile range (Q1 –Q3). For an assessment of distinctions used nonparametric criterion of Mann – Whitney.Results. In 1 days in response to high-intensity light influence there is a reflex strengthening of synthetic function of exorbital lacrimal glands. For the 7th days the first signs of violation of functioning with development of hydropic dystrophy in the lacrimacytes appear. By 14th days fibrous changes develop, in a glandular parenchyma harderization sites appear. For the 30th days the nuclear pycnosis of separate lacrimacit, accumulation of a lipofuscin in cytoplasm is observed.Conclusion. The obtained data allow to estimate in dynamics compensatory and adaptive reactions of lacrimal gland in response to high-intensity light influence from the moment of the beginning of their development before emergence of the first signs of a decompensation.

Purpose: this study morphological changes the exorbital lacrimal glands at experimental impact on an organ of vision of high-intensity light. Material and methods. White not purebred rats males (n = 40) were subjected to continuous influence of light intensity by 3500 lx within 1, 7, 14 and 30 days, the control group (n = 10) contained in conditions of natural lighting (20 lx). Exorbital lacrimal glands fixed in formalin, embedded in paraffin wax, stained hematoxylin-eosine. By means of an oculary insert of Avtandilov counted specific volumes of output channels, an epithelium, stroma and vessels of exorbital lacrimal glands, defined an epitelio/stroma ratio. The analysis of data was carried out by methods of descriptive statistics with calculation of a median (Ме) and interquartile range (Q1 –Q3). For an assessment of distinctions used nonparametric criterion of Mann – Whitney. Results. In 1 days in response to high-intensity light influence there is a reflex strengthening of synthetic function of exorbital lacrimal glands. For the 7th days the first signs of violation of functioning with development of hydropic dystrophy in the lacrimacytes appear. By 14th days fibrous changes develop, in a glandular parenchyma harderization sites appear. For the 30th days the nuclear pycnosis of separate lacrimacit, accumulation of a lipofuscin in cytoplasm is observed. Conclusion. The obtained data allow to estimate in dynamics compensatory and adaptive reactions of lacrimal gland in response to high-intensity light influence from the moment of the beginning of their development before emergence of the first signs of a decompensation.

The article presents the results of immunocorrecting properties of dry extract fractions of C. geoides (Rosaceae) for experimental immunodeficiency. Since the BAC fractions action relinquishes to the action of integral extract, the isolation of active substances is not reasonable

Проведено доклиническое исследование иммунокорригирующего действия суммарных препаратов из сырья эфиромасличного растения Coluria geoides (Pall.) Ledeb. (Rosaceae) при экспериментальном иммунодефиците. Исследуемые препараты устраняли проявления иммунодефицита, развивающиеся при применении циклофосфана: угнетение синтеза антиэритроцитарных антител-агглютининов и пролиферативных процессов в селезенке. Под влиянием препаратов C. geoides абсолютное число кариоцитов и количество антителообразующих клеток селезенки достоверно превышали перечисленные показатели в группе животных с экспериментальным иммунодефицитом, достигая в отдельных случаях фоновых значений. Изучаемые препараты оказывали более выраженное стимулирующее действие на синтез специфических иммуноглобулинов и пролиферацию антителообразующих клеток селезенки, чем настойка эхинацеи. Препарат С-2 (экстракт из подземных органов и травы C. geoides , полученный методом перколяции 70 % этанолом) наиболее перспективен для углубленного исследования с целью разработки нового эффективного иммунокорректора.

The article presents the results of influence estimation of dry extract fractions of C. geoides (Rosaceae) at different stages of cell-mediated immune response in DHS reaction. Fraction of water-soluble BAC more actively stimulated the synthesis of pro-inflammatory cytokines at the stage of DHS solution

Introduction: Differentiation between infection and sterile inflammation is one of the most difficult medical problems and is relevant in many clinical situations. Scintigraphy with radiolabeled antibiotics, еspecially labeled fluoroquinolones, is a promising tool for diagnosing bacterial inflammation. We have attempted to synthesize 99m Tc-norfloxacin and studied its properties in experiment. Methods: In present study we labeled norfloxacin with 99m Tc, determined its radiochemical purity by thin-layer chromatography procedure, compared the bactericidal activity of 99m Tc-norfloxacin and unlabelled norfloxacin by disk diffusion, performed in vitro binding assays and evaluated the feasibility of 99m Tc-norfloxacin to image soft-tissue infections in rat modal of thigh muscle infection. Scintigraphy was performed at 30 min, 90 min and 18 h post injection. Abscess –to–normal-site ratios were calculated. Results: In this study 99m Tc-norfloxacin with high radiochemical purity and low colloid content was synthesized. Disk diffusion method showed that 99m Tc-norfloxacin retains bactericidal properties of unlabelled norfloxacin. In vitro binding studies demonstrated small degree of the tracer binding with S. aureus and ability of 99m Tc-norfloxacin to bind with killed as well as alive bacteria. Uptake of the tracer was clearly visible in infected muscles and not visible in sterile inflammed muscles. Conclusion: The 99m Tc-norfloxacin retains bactericidal properties of unlabelled norfloxacin. The tracer demonstrated small degree of S. aureus binding both with killed as well as alive bacteria. Studies which were performed in vivo in rats with a model of thigh muscle infection showed good ability of the radiopharmaceutical to image the infection.